The present invention relates to a laminated glazing comprising a carrier film.
Laminated glazings comprising a carrier film are known. Typically the carrier film is between two plies of bonding resin, which are arranged between two plies of glazing material. The carrier film is typically made of an electrically insulating thermoplastic material and carries an electrically conductive coating. The electrically conductive coating is used to provide infrared reflection, heatability or an antenna function. In the case of a heated coated glazing, an external circuit is connected to the electrically conductive coating by means of a busbar, so as to achieve a required distribution of heating current.
Methods of manufacturing such laminated glazings, including the steps of shaping, degassing and using pressure and heat to join the constituents of the laminated glazings to one another, are known in the art.
A known problem with laminated glazings containing a carrier film is optical distortion due to wrinkles in the carrier film. Wrinkles are formed during manufacture of curved laminated glazing, where a carrier film is incapable of conforming to a radius of curvature of the curved laminated glazing. Wrinkles are visible as optical distortion in reflected light.
U.S. Pat. No. 6,242,088 (Pilkington/Costa) solves the problem of wrinkle formation in a carrier film by providing a bi-axially stretched carrier film, coextensive with plies of glazing material and having a heat shrinkage co-efficient in a particular range. US20110097572 (Central/Yonekura) prevents wrinkles related to heat shrinkage by forming a two-layer or three-layer laminated film containing a carrier film, which is coextensive with plies of glazing material, as a step in a manufacturing process.
WO0151279 (SIV/Bolognese) solves the problem of wrinkle formation by reducing the size of the carrier film, so the outer edge of the carrier film lies within the outer edge of two plies of glazing material, i.e. the carrier film is no longer coextensive with the plies of glazing material. In preferred embodiments, a distance between an edge of the carrier film and an edge of the plies of glazing material is at least 10 mm and is substantially constant around the entire circumference of the laminated glazing.
It is an object of the present invention to provide a laminated glazing comprising a carrier film, further comprising an alternative means for preventing wrinkle formation in the carrier film.